PostgreSQL is being used for mission critical applications in enterprises and FOSS projects. As part of a SAAS (Software As a Service) solution, database uptime is even more critical. However, databases need just as much maintainance as application code, and if the database isn't designed correctly, even more.

With large databases, refactoring the database tends to cause long downtimes while data is moved around or table structure changes wait for lock availability. Some database refactorings need exclusive locks which block reads as well.